Metallized film and decorative articles made therewith

ABSTRACT

A metallized film comprises an opaque, continuous layer of metal on an aliphatic polyurethane substrate. The polyurethane substrate displays a glass transition temperature of about 25° to 110° C. and a melting temperature greater than or equal to 200° C. Decorative articles can be made with the metallized film.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to metallized films and, moreparticularly, to metallized polyurethane films. This invention alsorelates to decorative articles made with such metallized films.

[0003] 2. Description of the Related Art

[0004] Metallized films, that is, films comprising a polymeric substrateon which has been deposited a layer of metal, are often employed in, forexample, the automotive, furniture, stationery, interior buildingmaterial, and advertising industries to provide an aesthetic ordecorative enhancement to manufactured articles. Such films, in order tobe commercially useful as decorative and aesthetic enhancements, shouldpossess several characteristics.

[0005] For example, the substrate layer should be highly transparent soas not to detract from the reflective quality of the metal layer and theoverall appearance of the article. The films should also exhibit goodheat stability, especially when employed in the construction of outdoorsigns, motor vehicles and other articles where high temperatures may beencountered. For example, the interior of a motor vehicle on a warm,sunny day in certain climates may experience temperatures in excess of90° C.

[0006] Flexibility is another desirable quality because flexible filmsare more. readily applied to rough or uneven surfaces and multifacetedarticles having a compound geometry. In still other applications,metallized films may be embellished with printed messages, decorativepatterns, or complementary, decorative, transparent, colored layers.Metallized films, in order to be commercially useful, should readilyaccept printing and should be susceptible to the adhesion of furtherdecorative layers thereto. Such films should also possess excellentadhesion between the metal and substrate layers. The films should becapable of being applied in an economical manner and retain a qualityappearance without developing bubbles, wrinkles, swells or the like.Once applied, the film, should remain durable and exhibit goodresistance to a wide variety of weathering and environmental conditions.

[0007] Metallized films that display a bright, highly polished, highlyreflective mirrorlike appearance would be especially desirable if theycould be bonded to a reinforcing layer since they could be used tosimulate conventional chrome plated components, such as are found onmotor vehicles.

[0008] Various metallized films are presently known. For example,metallized polyester films have been commercially available for manyyears.

[0009] U.S. Pat. No. 5,164,245 (Suzuki) discloses a metallizedmultilayer film comprising a first substrate layer, a second substratelayer on the first substrate layer, and a layer of metal on the secondsubstrate layer. The first substrate layer comprises from 0 to about 40parts by weight poly(vinylidine fluoride) and, correspondingly, from 100to about 60 parts by weight poly(methyl methacrylate). This patentreports that metallized acrylic films are also known.

[0010] U.S. Pat. No. 4,101,698 (Dunning et. al.) discloses a transferlaminate having a flexible transparent or translucent elastomeric layer(e.g., polyurethane) and a layer of metal bonded to the elastomericlayer in separate, microscopically discontinuous planar quantities ofhigh reflectivity. The metal layer forms an apparent visually continuousreflective surface.

SUMMARY OF THE INVENTION

[0011] This invention relates to metallized films that comprise anopaque, continuous layer of metal in direct contact with an aliphaticpolyurethane substrate. The polyurethane substrate displays a glasstransition temperature of about 25 to 110° C. and a melting temperaturegreater than or equal to 200 ° C. The metal layer may be tin, chromium,nickel, stainless steel, copper, aluminum, indium, gold, silver, oralloys thereof.

[0012] The polyurethane substrate may be derived from an aqueousurethane dispersion and may advantageously include a small amount of acrosslinking agent to desirably shift or provide the the glasstransition temperature and/or to shift the melting temperature.

[0013] Other optional, though highly desired, layers that may form apart of the metallized film include a primer for improving the adhesionbetween the metal layer and a subsequent surface. The metallized filmsmay also include a color layer on the polyurethane substrate and aprotective clear coat layer on the color layer.

[0014] Various decorative articles including multifaceted articleshaving a compound geometry may be made using the metallized films of theinvention. The metallized film may be placed in a conventional vacuumforming mold and a polymeric reinforcing layer may be added thereto.Attachment of the resulting decorative article to a subsequent surfacemay be facilitated by the use of an adhesive on the reinforcing layer.

[0015] Decorative articles made with the metallized films of theinvention simulate the appearance of conventional chrome plated parts.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention will be more fully appreciated with reference tothe following drawings in which similar reference numerals designatelike or analogous components throughout and in which:

[0017]FIG. 1 is an enlarged cross-sectional view of a metallized filmaccording the invention; and

[0018]FIG. 2 is an enlarged cross-sectional view of an articleincorporating a metallized film according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Turning now to the drawings, FIG. 1 is an enlargedcross-sectional view of a metallized film 10 according to the invention.Film 10 comprises a substrate 12 that comprises (and more preferablyconsists essentially of) a polyurethane material upon which has beendeposited a continuous, opaque layer of metal 14. By “film” is meant astructure that is substantially, longer, wider, or both longer and widerthan it is thick as well as being flexible. The polyurethane substrateshould be sufficiently transparent or translucent so as to. permit metallayer 14 to be viewed therethrough, especially when the metal layerprovides a decorative feature.

[0020] Useful polyurethane substrates are derived from aqueousdispersions of aliphatic urethane resins, display a glass transitiontemperature of about 25° to 110° C., and exhibit a melting temperaturegreater than or equal to 200° C. The glass transition temperature andmelting temperature are determined by thermal mechanical analysis usingthe test apparatus set-up described in ASTM D1525-87, “Standard TestMethod for Vicat Softening Temperature of Plastics,” although Vicatsoftening temperature is not measured. More specifically, a substratesample approximately 2 to 3 mm thick is heated from −100° C. to 250° C.at a rate of 15° C. per minute. A flat tipped penetration probe (needle)having a circular cross sectional area of 1 mm² and loaded with 5 g isused. The glass transition temperature is the region in which the firsttransition occurs in the thermal mechanical analysis. The meltingtemperature is reached when the penetration probe meets no resistance.

[0021] Examples of suitable, commercially available aqueous, aliphaticurethane dispersions include the ZENECA NEOREZ family of materials fromICI Chemicals, Inc. such as XR 9699, XR 9679, and XR 9603. Also usefulis MILES BAYHDROL 121 from Miles, Inc.

[0022] In some situations, the addition of a small amount (e.g., about2.5% or less based on the solids content of the urethane dispersion) ofa crosslinking agent may be advantageous in shifting or providing theglass transition temperature and/or the melting temperature of theresulting polyurethane to the desired range. Useful crosslinking agentsinclude diaziridines, such as NEOCRYL CX-100, available from ICIChemicals, Inc. Another useful additive is a coalescing solvent such asbutyl carbitol. The polyurethane substrate may also include conventionalcolorants such as pigments, dyes and inks for providing a colored ortinted appearance to the substrate. Ultraviolet radiation stabilizersmay also be incorporated depending on the ultimate application of themetallized film.

[0023] The polyurethane substrate typically has a thickness of about 20to 28 microns (μm). If the substrate is too thin, it may not readilystretch or conform to articles having a compound shape. On the otherhand, if the substrate is too thick, it may be difficult to form.

[0024] Continuous, opaque metal layer 14 has a highly reflective, highlypolished, mirrorlike appearance. By “continuous” it is meant that metallayer 14 forms a substantially uninterrupted layer on the polyurethanesubstrate as opposed to a field of closely spaced dots or other separatesegments. By “opaque” it is meant that metal layer 14 can not be readilyseen through under normal use conditions. A typical metal density wouldbe about 0.03 mg/cm². Virtually any ductile metal may be used to providelayer 14 although tin, chromium, nickel, stainless steel, copper,aluminum, indium, gold, silver, and alloys thereof are particularlypreferred.

[0025] Metallized film 10 may optionally include a primer layer 16 forpromoting adhesion between metal layer 14 and any subsequently providedreinforcement or backing layer, such as layer 22 shown in FIG. 2. Theprimer layer may be provided by any hydroxy functional vinyl resin(e.g., VAGH from Union Carbide Corp.), any carboxyl functional resin(e.g., VMCH from Union Carbide Corp.), or any amine functional resin.Polyamide primer layers are also useful such as MACROMELT 6240 fromHenkel. The primer layer is typically about 6 to 13 μm thick. Metallayer 14 is in direct contact with the polyurethane substrate. By“direct contact” it is meant that there are no intervening tie layers orstabilizing layers.

[0026] Other optional layers include color layer 18 which may besupplemented with an overlying, protective clear coat layer 20. Colorlayer 18 is visible though clear coat layer 20 and provides color tofilm 10 by the incorporation into layer 16 of one or more of thefollowing color agents: pigments (organic or inorganic), dyes, inks,mica, glass particles, glass beads, etc. A typical composition for colorlayer 18 is an acrylic/vinyl resin binder containing a pigment. Clearcoat layer 20 provides abrasion resistance and environmental weatheringresistance to color layer 18 and is typically provided by asolvent-based polyurethane.

[0027] Turning now to FIG. 2, film 10 comprising polyurethane substrate12 and metal layer 14 is secured to a polymeric reinforcing or backinglayer 22 which is useful in providing a decorative article 24 and thelike for subsequent attachment to various surfaces. Reinforcing orbacking layer 22 may be provided a wide variety of materials such asurethanes, acrylonitrile-butadiene-styrenes, thermoplastic polyolefins,and the like. In general, virtually any thermoplastic molding compoundmay be used.

[0028] To facilitate the attachment of decorative article 24 to asubsequent surface, the article may be provided with an attachmentsystem 26. The attachment system may be provided by, for example, anacrylic, pressure-sensitive adhesive foam tape 28 that is temporarilyprotected by a removable release liner 30, such as a silicone treatedpaper or polyester film.

[0029] Metallized film 10 may be readily and easily formed. For example,the aqueous urethane dispersion for providing polyurethane substrate 12may be cast onto a suitable release liner such as a release coatedpolyester film. The cast urethane dispersion is then dried to removewater. The polyurethane coated release liner is then vapor coated toopacity with the desired metal using conventional vapor coatingtechniques. Optional primer-layer 16 may then be added, if desired, bycoating, hot lamination, or the like, depending on the nature of theprimer layer.

[0030] If metalized polyurethane film 10 is to be subsequently formedinto a decorative article, the polyester release liner is removed andthe metallized film is placed in a conventional vacuum forming mold withthe metallized surface facing away from the mold surface. Typically, themold is heated to about 52° C. and a vacuum sufficient to enable thefilm to conform to the contoured mold cavity is applied. Thepolyurethane substrates us d in the invention are flexible, stretchable,and readily vacuum formed into shapes having a compound geometry.

[0031] Optional reinforcing or backing layer 22 may be used to backfillthe mold by being deposited into the mold cavity against the metallizedsurface of the film. Attachment system 26 may be applied using, forexample, heated nip rollers in the case of foam tape. The reinforcinglayer is typically oven cured followed by any optional decorating suchas the casting and curing of color layer 18 and protective clear coat20. The resulting decorative articles display a highly reflective,highly polished, mirrorlike finish.

[0032] The invention will be more fully appreciated with reference tothe following non-limiting examples.

EXAMPLES 1 to 11

[0033] Examples 1 to 11 illustrate the use of different aliphaticurethane dispersions to provide polyurethane substrate 12 as well as theeffect of including or excluding a crosslinking agent. Table 1 belowindicates various commercially available aliphatic urethane dispersionsthat were used in forming the polyurethane substrate and the presence orabsence of a crosslinking agent. The “% Crosslinking Agent” refers tothe percent of NEOCRYL CX-100 that was added based on the total solidscontent of the urethane dispersion. In each example, the urethanedispersion also included 10% butyl carbitol (based on the solids contentof the urethane dispersion).

[0034] The compositions of Table 1 (including butyl carbitol) were castonto release coated polyester films and dried for 2 minutes at about 93°C. and then for 3 minutes at about 149° C. so as to provideapproximately 25 μm thick polyurethane substrates. The polyurethanesubstrates with the polyester film were then placed in a DENTON VacuumDV-515 bell jar vapor coating machine and vapor coated to opacity withtin metal (about 0.2 mg/cm² metal density).

[0035] After vapor coating, the polyester film was removed and themetalized polyurethane substrate was placed in an approximately 52° C.conventional vacuum forming mold and vacuum drawn into small decorativeparts having a pentagonal shape, a compound geometry, a diameter ofapproximately 2.54 cm, and a thickness of about 0.25 cm.

[0036] A reinforcing layer provided by a two-part polyurethane castingresin that comprised equal equivalents of LEXOREZ 5901-300 polyesterpolyol (available from Inolex Chemical Co.) (to which was added a traceamount of dibutyl tin dilaurate catalyst) and DESMODUR N-100polyisocyanate (available from Miles, Inc.) was poured into the moldcavity and in contact with the layer of tin metal. An acrylic pressuresensitive adhesive foam tape was then laminated to the reinforcinglayer.

[0037] The contents of the vacuum forming mold were heated for about 5minutes at about 52° C. to cure the reinforcing layer. The resultingmolded part was removed from the mold, trimmed, and applied to a paintedsteel panel with the acrylic foam tape.

[0038] Also shown in Table 1 are the glass transition temperature (Tg)and the melting temperature (Tm) (as determined by the thermalmechanical analysis procedure described more fully hereinabove), theobserved results being reported to the nearest 0.1° C. TABLE 1 % Cross-linking Tg Tm Example Urethane Resin Agent (° C.) (° C.) 1 ZENECA NEOREZXR 9699 1 44.1 221.6 2 ZENECA NEOREZ XR 9699 0 50.5 202.6 3 ZENECANEOREZ XR 9679 1 106.5 214.3 4 MILES BAYHYDROL 110 0 47.9 199.1 5 MILESBAYHYDROL 121 0 N.O. 216.1 6 MILES BAYHYDROL 121 1 64.6 225.2 7 ZENECANEOREZ XR 9603 1 25.9 219.7 8 ZENECA NEOREZ XR 9603 0 41.5 205.3 9 75%ZENECA NEOREZ XR 9699 1 34.7 233.7 25% MILES BAYHYDROL 121 10 50% ZENECANEOREZ XR 9699 1 53.4 228.9 50% MILES BAYHYRDOL 121 11 25% ZENECA NEOREZXR 9699 1 52.6 229.6 75% MILES BAYHYRDOL 121

[0039] Upon removal from the vacuum forming mold, the parts of each ofexamples 1 to 11 displayed a bright, highly reflective, highly polished,mirrorlike appearance that simulated the look of conventional chromeplated parts. Even after seven days in a 93° C. oven and 2000 hours ofaccelerated xenon exposure weathering (based on SAE J1960 Jun. 89“Accelerated (G-26 type BH) Exposure of Automotive Exterior MaterialsUsing a Controlled Irradiance Water Cooled Xenon Arc Apparatus”) theparts of examples 1 to 3 and 6 to 11 did not appreciably change inappearance and were considered weatherable. The part of example 4 turneda dull gray color and the part made in example 5 lost a small amount ofits original bright appearance. consequently, examples 4 and 5 wereconsidered unacceptable.

[0040] Table 1 illustrates the benefit of providing a polyurethanesubstrate having a glass transition temperature of about 25° to 110° C.and a melting temperature greater than or equal to 200° C. Comparing theresults obtained for examples 5 and 6 shows the beneficial effect ofincluding a small amount of a crosslinking agent in the polyurethaneformulation. The addition of 1% of a crosslinking agent in thepolyurethane formulation of example 5 resulted in a suitable substrate(example 6). Examples 9 to 11 indicate that blends of more than oneurethane dispersion provide useful polyurethane substrates.

EXAMPLES 12 to 16

[0041] Examples 12 to 16 were prepared utilizing the procedure describedin conjunction with example 1 and further included a primer layer on themetal layer for providing enhanced adhesion between the metal layer andthe reinforcing layer. The primer of each example was an approximately13 μm thick precast layer of MACROMELT 6240 polyamide that was hotlaminated to the metal layer using a pair of nip rollers heated to 121°C. and a feed rate of about 3.05 meters per minute. The metal layer wasalso varied, as shown below in Table 2. TABLE 2 Example Metal layer 12Tin 13 Nickel 14 Chromium 15 Stainless Steel 16 Inconel

[0042] Upon removal from the vacuum forming mold, each part exhibited abright, highly reflective, highly polished, mirrorlike appearance thatsimulated conventional chrome plated parts. After 7 days in a 93° C.oven and 2000 hours of accelerated weathering, none of the partsappreciably changed in appearance. Table 2 indicates that various metalsmay be applied to the polyurethane substrate so as to form a metallizedfilm in accordance with the invention.

EXAMPLE 17

[0043] A metallized film according to the invention was prepared byblending ZENECA NEOREZ 9699 with 2% NEOCRYL CX-100 crosslinking agent(based on the solids content of the urethane dispersion) and 10% butylcarbitol (based on the solids content of the urethane dispersion),casting on a release coated polyester film, and drying for 2 minutes atabout 93° C. and then for 3 minutes at about 149° C. so as to yield anapproximately 20 μm thick polyurethane substrate. The polyurethanesubstrate was placed in a DENTON Vacuum DV-515 bell jar vapor coatingmachine and was vapor coated to opacity with tin metal. A 13 μm thickMACROMELT 6240 polyamide primer layer was then hot laminated to themetal layer using a pair of 121° C. nip rollers and a 3.05 meters perminute feed rate. The primed, vapor coated polyurethane substrate wasthen removed from the polyester film and placed in a conventional vacuumforming mold that had been heated to approximately 54° C.

[0044] A polyurethane reinforcing layer was provided by pouring into thedepression in the vacuum forming mold a mixture comprising equalequivalents of LEXOREZ 5901-300 polyester polyol (to which was added atrace amount of dibutyl tin dilaurate catalyst) and DESMODUR N-100polyisocyanate followed by the addition of an acrylic, pressuresensitive foam adhesive tape. The reinforcing layer was cured at about54° C. for about 5 minutes. The resulting part exhibited a bright,highly reflective, highly polished, mirrorlike appearance that simulatedconventional chrome plated parts. No appreciable change in appearancewas observed following 7 days in a 93° C. oven.

EXAMPLE 18

[0045] 7.2 g. MONASTRAL YT-919D gold pigment (available from Ciba Geigy,Inc.) was ball milled with 220 grams (g) of ZENECA XR9699 aliphaticurethane dispersion and 20 g butyl carbitol for 21 hours. A small amountof this dispersion, sufficient to give a transparent yellow color, wasadded to a blend of 100 g ZENECA XR-9699, 10 g butyl carbitol, and 0.3 gRohm & Haas TRITON GR-7M. This blend was cast on a release coatedpolyester film and dried for 5 minutes at 93° C. and then for 3 minutesat 149° C. to give an approximately 25 μm thick film. After vaporcoating to capacity with tin metal, the sample was primed and formed asin example 12 to give a decorative product having a bright, highlyreflective, highly polished gold appearance. The part showed noappreciable change in appearance after 7 days in a 93° C. oven and 2000hours of accelerated weathering.

EXAMPLES 19 to 22

[0046] Examples 19 to 22 were prepared to evaluate the utility ofalternative substrate materials. In each case, the procedure describedin conjunction with example 17 was followed except using a substratematerial selected according to Table 3 below. TABLE 3 Example Substrate19 Polyethylene terephthalate 20 Polyvinylidene fluoride 21 Polyvinylchloride 22 Polybutylene terephthalate

[0047] Examples 20 to 22 resulted in products having a hazy appearancethat did not simulate conventional chromed plated parts and wereconsidered unacceptable. Example 19, while providing a part thatsimulated a conventional chrome plated part, could not be readily formedin the vacuum mold and, as a result, was considered unacceptable.

[0048] Numerous variations and modifications-are possible within thescope of the foregoing specification and drawings without departing fromthe spirit of the invention which is defined in the accompanying claims.

The embodiments for which an exclusive property or privilege is claimed are defined as follows:
 1. A metallized film comprising a continuous, opaque layer of metal in direct contact with an aliphatic polyurethane substrate that has a glass transition temperature of about 25° to 110° C. and a melting temperature greater than or equal to 200° C.
 2. A metallized film according to claim 1 wherein the metal is selected from the group consisting of tin, chromium, nickel, stainless steel, copper, aluminum, indium, gold, silver, and alloys thereof.
 3. A metallized film according to claim 1 wherein the polyurethane substrate is derived from an aqueous urethane dispersion.
 4. A metallized film according to claim 1 wherein the layer of metal is visible through the polyurethane substrate.
 5. A metallized film according to claim 1 wherein the polyurethane substrate includes a crosslinking agent therefor.
 6. A metallized film according to claim 1 further comprising a primer layer on the layer of metal for improving the adhesion of the layer of metal to a subsequent material.
 7. A metallized film according to claim 1 further comprising a color layer on the polyurethane substrate.
 8. A metallized film according to claim 7 further comprising a protective clear coat layer on the color layer.
 9. A metallized film according to claim 8 further comprising a primer layer on the layer of metal for improving the adhesion of the layer of metal to a subsequent surface.
 10. A metallized film according to claim 9 wherein the layer of metal is visible through the protective clear coat layer, the color layer, and the polyurethane substrate.
 11. A decorative article comprising a metallized film according to claim 1 secured to a reinforcing layer.
 12. A decorative article according to claim 11 further comprising a primer layer between the layer of metal and the reinforcing layer.
 13. A decorative article according to claim 12 further comprising an adhesive on the reinforcing layer for attaching the decorative article to a subsequent surface.
 14. A decorative article according to claim 11 wherein the decorative article has a highly reflective, highly polished, mirrorlike appearance.
 15. A decorative article according to claim 11 that shows no appreciable change in appearance after 7 days in a 93° C. oven.
 16. A decorative article according to claim 11 that shows no appreciable change in appearance after 2000 hours of xenon arc accelerated weathering exposure. 